A common claim in aquariums and terrariums the world round. The poison of this animal is so potent that it can kill some ridiculously large number of men, horses, elephant, Belgiums. Why would an animal need a poison so powerful? It is not like they can dose it out and actually spread it among so many victims (or have the stamina to do it even if they could dose it out).
I guess that a more powerful poison can kill the victim faster which helps the animal surviving the encounter but there has to be a point of diminishing returns. I am also assuming that a more powerful poison is more expensive to make, which might not be the case.
So, what gives? Why have a poison that can kill hundreds of victims and use it all in one?
Its victims are bigger and more resistant than men.
It produces the venom when it can, and stores it, which is more reliable than trying to produce it in more exacting quantities.
Also, and obviously since this creature exists, storing large am’ts of venom does not select against it. In other words, it comes at no cost of survival to store it (and if it DOES come at cost, it must be a cost relative to some other creature that is benefiting ever-so-slightly and gradually overtaking said species until it no longer exits). So, lest you can see the future, the jury is out. All extinct creatures were once around to be observed. Think about it.
See, that’s the bit, right there, where your logic might be breaking down. The incredibly powerful toxin may just simply be really efficient at surviving breakdown on its trip to the killing center of the target. It’s not really trying to be enough to kill a thousand elephants per se, just that the combined immune systems of a thousand elephants isn’t enough to destroy the toxin. That’s not what makes a toxin, metabolically speaking, “expensive” to make.
I remember one Nature special, a blue ringed octopus, one of those “most toxic” animals couldn’t reach a shrimp to bite it with its venom. So it just hung around the back of the coral outcrop, pumping it’s venom into the water, until the shrimp got woozy and fell out. I don’t have a video cite, but that’s one use for a large amount of powerful toxin – spray dispersal, the next evolutionary step. Like the spitting cobra.
The creature may use only a tiny fraction of the “hundreds of X” dose in a single envenomation. A “drop” is a huge amount of venom for many species, more than they can make or store at a time. Also, the venomous creature may need a venom that will take effect quickly, perhaps to incapacitate prey before it can escape, or a predator before it can kill. The fact that the venom can incapacitate or kill larger creatures over a longer period of time is a byproduct of this selection.
The golden lancehead, for instance, preys heavily on birds; its venom is faster-acting and roughly five times as potent as that of a related species with different prey opportunities.
Chironex fleckeri is considered the most lethal jellyfish in the world. A full-grown specimen will have a bell about 25cm in diameter and tentacles estimated to hold enough venom to kill 60 human adults. This venom is distributed in nematocysts along 60 tentacles, each about 3 meters long. A small fish, the jelly’s typical prey, would only contact a small portion of a tentacle, so it would be exposed to only a minute amount of venom, yet it must be disabled before it can tear free (possibly ripping the tentacle off in the process), or the jelly will go away hungry and possibly injured. It takes the equivalent of a whole tentacle, more or less, to kill a human adult (though it can do so in as little as 3 minutes with sufficient exposure).
C. fleckeri has been described as the world’s deadliest venomous animal, by the way. Since its bragging rights cap at about 60 adults, the “hundreds of X” claims should probably be regarded as exaggerations.
Depending on context, “one drop” can be a pretty large volume. There is no single definition for “drop”, but according to wikipedia, it can be up to 1/12 ml (83 microliter). The venom gland of a small spider only contains a fraction of a microliter.
When talking about evolution, asking why is almost always a fruitless question. It’s part of the human condition that we always ask that question, but nature doesn’t care. Either the package deal works or it doesn’t.
It may also be related to some past advantage. Look at the pronghorn. It is faster than anything but a cheetah and it can keep up it’s fast speeds much longer than any cheetah.
The pronghorn lives in North America and once it starts running, there isn’t anything that can come close to catching it. So why does a pronghorn need to run so fast?
It’s theorized that in the very old days, the pronghorn needed to it. The cheetah for instance used to live in North America. Though a pronghorn can easily outlast a cheetah, the cheetah can best it for a short distance.
Therefore in the old days the pronghorn needed to be quick. But now that the cheetah is extinct in North America, the pronghorn has no real preditors as long as it can get a running start. Though the pronghorn is a very bad jumper and often when they encounter a sheep fence it will try to go under it.
I heard an explanation for one of the most poisonous snakes in Australia was that it lived in a very barren area. It might not encounter prey for days. When it did encounter prey, it had to kill it. Every time. Ergo, hugely poisonous bite.
I expect (in this case, at least) those snakes who bit something that didn’t die didn’t survive to pass on their slightly less poisonous genes.
I guess I had never considered that this famous drop is more than the animal actually carries and uses.
I also wondered about the cost of producing these toxins. I guess deadlier is not necessarily costlier. Some animals just hit the evolutionary jackpot and developed some super toxin instead of a tamer one.
They’re nasty little buggers, and their venom may well be more potent, but they’re not generally as lethal as sea wasps (C. fleckeri). This may just be because they’re much smaller, and don’t inject as much venom. Irukandji stings usually aren’t fatal if treated, and when they are, they take about 20 minutes to kill. A sea wasp sting, on the other hand, may kill you in less than 3 minutes–people are known to go into cardiac arrest before they can get back into a boat, let alone be treated.
A total of two deaths have been attributed to irukandji jellies, though they may well be responsible for more. Sea wasps, on the other hand, are blamed for at least one death a year in Australia, with a record of 67 one year, according to the Wikipedia entry.
Most (well, at least some) poisons are modified digestive enzymes and are no more expensive to make in the body than saliva, bile, etc. Of course, the venom is delivered in a more concentrated form than the enzymes in saliva, so there may be more calories per unit of fluid, but not necessarily more calories per unit of dry weight.
